code: def _test_array(self, df):
      train_idxs = np.random.rand(len(df)) < 0.8
      train = df[train_idxs]
      test = df[~train_idxs]
  
      predictor = predictor_from_problem(
          df,
          ProblemDefinition.from_dict(
              {
                  "target": "output",
                  "time_aim": 80,
              }
          ),
      )
      predictor.learn(train)
      predictor.predict(test)
  
file_path: lightwood/tests/integration/advanced/test_array.py
imports: import unittest
  import numpy
  import pandas
  from lightwood.api.types import ProblemDefinition
  from lightwood.api.high_level import json_ai_from_problem, code_from_json_ai, predictor_from_code, predictor_from_problem
label_desc: Use image node_id 1 for calling the TestArrayTarget obj's underlying member method code with example usage: obj._test_array(df) without return types